1. Field of the Invention
The present invention concerns an optoelectronic component, utilized in optical fibers data transmission systems. This optoelectronic component is a coupling device that comprises at least one electroluminescent diode and a photodiode: the assembly constituted by these two diodes is integrated in a standard sealing box for transistors. The invention applies more particularly to bidirectional connections through a single optical fiber called monofiber.
2. Background of the Prior Art
In a monofiber bidirectional optical connection, the single optical fiber transmits, in a direction called forward direction, the light which is emitted by an electroluminescent diode, commonly called a LED, placed at a first end of the fiber, and which is received by a photodiode placed at a second end of the fiber. In the other direction, that will be called the backward direction, the light emitted by a second LED, placed at the second end of the fiber, is received by a second photodiode, placed at the first end of the fiber. Thus at each end of the optical fiber, a LED and a photodiode are provided that must both be optically connected with to the adjacent end of the optical fiber. Known solutions for establishing this optical connection are generally rather bulky; the coupling devices are constituted by a housing or box the faces of which support the optical connecting devices. At least one connecting device is provided for the optical fiber, another connecting device for the LED in its microbox and yet another connecting device for the photodiode in its microbox. Inside the box enclosing the coupling device, simple means couple or connect the LED to the optical fiber and the photodiode to the optical fiber. The main drawback of these coupling devices, although they are simple, is their bulk; furthermore, due to the very small dimensions of the optical fibers used in bidirectional systems (50-100 .mu.m) these coupling devices require high machining accuracy at each connection made by means of connectors.
The optoelectronic component according to the invention has a far smaller volume than known coupling devices, and it can easily be aligned with the optical axis of the optical fiber. It comprises at least one LED and a photodiode, and at least one semitransparent mirror, but it is characterized in that the assembly is integrated in a standard transistor sealing, box or housing provided with a microlens on the planar surface of its cover. The LED and the photodiode are mounted side by side, on an insulating base plate, the DEL being located on the optical axis of the microlens and provided with an optical microbead, in order to concentrate its luminous radiation on the microlens. The photodiode receives the luminous radiation entering the box, or a part of the luminous radiation emitted by the DEL, by means of a set of mirrors positioned inside the cover or lid of the box; at least one semitransparent mirror is maintained in position by a piece machined face of which is opposed to the photodiode and assumes the function of a mirror.